The present invention relates to the use of a process and apparatus with a screw in a barrel for treating cellulosic materials in order to expand the materials, thereby making them more useful as animal feeds and for fermentation processes, for instance. In particular the present invention relates to a screw in a barrel process and apparatus which provides continuous processing of the cellulosic material using liquid ammonia which expands the cellulosic material while changing from a liquid to a gas upon exiting the apparatus.